Synergistic composition and method for selective weed control in rice

ABSTRACT

Compositions that contain, in admixture with one another, as active ingredient, on the one hand N-[2-(2-methoxyethoxy)-phenylsulphonyl]-N&#39;-(4,6-dimethoxy-1,3,5-triazin-2-yl)-urea of the formula ##STR1## and on the other hand one or two of the active ingredients of the formulae II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV and XV defined herein exhibit synergistic herbicidal action in rice.

This is a divisional of application Ser. No. 107,202 filed on Oct. 13,1987, now U.S. Pat. No. 4,840,663.

The present invention relates to a synergistic composition that containsa herbicidal active ingredient combination that is extremely suitablefor selective weed control in rice crops. The invention relates also toa method for controlling weeds in rice and to the use of the novelcomposition.

The most common and important weeds in rice at present are species ofthe genera Alisma (water plantain); Ammania; Cyperus (cypress grass);Echinochloa (barnyard grass); Eleocharis (spike rush); Fimbristylis(fringe rush); Scirpus (bulrush) and Monochoria.

N-[2-(2-methoxyethoxy)-phenylsulphonyl]-N'-(4,6-dimethoxy-1,3,5-triazin-2-yl)-urea of the formula I ##STR2## has provedto be an excellent selective herbicide against weeds in crops of usefulplants That active ingredient is described, together with itsmanufacture and use, in U.S. Pat. No. 4,479,821.

In addition, compounds of the formulae II, III, IV, V, VI, VII, VIII,IX, X, XI, XII, XIII, XIV and XV are also known as selective herbicides.Some of them are already commercially available ##STR3## in which R¹represents C₁ -C₄ -alkoxycarbonyl or C₁ -C₄ -alkoxy, covers thefollowing embodiments

IIa: 5-(2,4-dichlorophenoxy)-2-nitrobenzoic acid methyl ester, knownfrom Pesticide Manual 5th Ed. (1977), 41, The British Crop ProtectionCouncil, London; and

IIb: 4-(2,4-dichlorophenoxy)-2-methoxynitrobenzene, known from PesticideManual 5th Ed. (1977), 175, The British Crop Protection Council, London;##STR4## in which R² represents chlorine or methyl, covers the followingindividual active ingredients:

IIIa: 2,4-dichlorophenoxyacetic acid, known from Pesticide Manual 5thEd. (1977), 330, The British Crop Protection Council, London; and

IIIb: 4-chloro-2-methylphenoxyacetic acid, known from Pesticide Manual5th Ed. (1977), 330, The British Crop Protection Council, London.

The formula IV ##STR5## in which R³ represents ethyl or1,2-dimethylpropyl, covers the following embodiments

IVa: 2,4-bis-ethylamino-6-methylthio-1,3,5-triazine, known fromPesticide Manual 5th Ed. (1977), 472, The British Crop ProtectionCouncil, London; and

IVb:2-[(1,2-dimethylpropyl)amino]-4-ethylamino-6-methylthio-1,3,5-triazine,known from Pesticide Manual 5th Ed. (1977), 197, The British CropProtection Council, London ##STR6## in which R⁴ represents C₁ -C₄-alkoxy or C₁ -C₄ -alkoxymethyl, covers the following embodiments:

Va: N-(butoxymethyl)-2-chloro-N-(2,6-diethylphenyl)-acetamide, knownfrom Pesticide Manual 5th Ed. (1977), 60, The British Crop ProtectionCouncil, London; and

Vb: N-(propoxyethyl)-2-chloro-N-(2,6-diethylphenyl)-acetamide, knownfrom pesticide Manual 7th Ed. (1983), 9970, The British Crop ProtectionCouncil, London

The formula VI ##STR7## in which R⁵ represents2-(2-chloroethoxy)-phenyl, 2-methoxycarbonylbenzyl or4-ethoxycarbonyl-1-methyl-5-pyrazolyl, R⁶ represents methoxy or methyland A represents nitrogen or the methine group, covers especially thefollowing individual substances

VIa:N-[2-(2-chloroethoxy)-phenylsulphonyl]-N'-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-urea,known from European Patent EP-A-44807;

VIb:N-(2-methoxycarbonylbenzylsulphonyl)-N'-(4,6-dimethoxypyrimidin-2-yl)-urea,known from EP-A-51466; and

VIc:N-(4-ethoxycarbonyl-1-methylpyrazol-5-ylsulphonyl)-N'-(4,6-dimethoxypyrimidin-2-yl)-urea,known from EP-A-87780. ##STR8## in which R⁷ represents 1-piperidinyl,1-hexahydroazepinyl or diethylamino and R⁸ represents ethyl,4-chlorobenzyl or 1,1-dimethylbenzyl, covers especially the followingspecific embodiments:

VIIa: S-ethyl-N,N-hexamethylene thiocarbamate, known from PesticideManual 5th Ed. (1977), 369, The British Crop Protection Council, London;

VIIb: S-1,1-dimethylbenzyl-N,N-pentamethylene thiocarbamate, known fromJP-PS 51 098 331; and

VIIc: S-4-chlorobenzyl-N,N-diethyl thiocarbamate, known from PesticideManual 5th Ed. (1977), 106, The British Crop Protection Council, London

The compounds of the formulae VIII, IX, X, XI, XII, XIII, XIV and XV arerepresented by the following formulae:

3,7-dichloroquinoline-8-carboxylic acid of the formula VIII ##STR9##known from DE-OS 3 108 873; 2-(2-naphthyloxy)-propionic acid methylester of the formula IX ##STR10## known from DE-OS 2 247 076;N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitroaniline of the formula X##STR11## known from Pesticide Manual 7th Ed. (1983) 9390, The BritishCrop Protection Council, London;

5-tert.-butyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2-oneof the formula XI ##STR12## known from Pesticide Manual 5th Ed. (1977),393, The British Crop Protection Council, London;

3-isopropyl-1H-benzo-2,1,3-thiadiazin-4-one-2,2-dioxide of the formulaXII ##STR13## known from Pesticide Manual 5th Ed. (1977), 35, TheBritish Corp Protection Council, London;

2-(2-benzothiazolyloxy)-N-methylacetanilide of the formula XIII##STR14## known from DE-OS 2 822 155; 3,4-dichloropropionanilide of theformula XIV ##STR15## known from Pesticide Manual 5th Ed. (1977), 439,The British Crop Protection Council, London; and

S-2-methylpiperidinocarbonylmethyl-O,O-dipropyldithiophosphoric acidester of the formula XV ##STR16## known from Pesticide Manual 5th Ed.(1977), 427, The British Crop Protection Council, London

It has surprisingly been found that a quantitatively variablecombination of two active ingredients, on the one hand active ingredientI and on the other hand an active ingredient selected from the classesII, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV and XV,produces a synergistic effect that is capable of controlling themajority of all important rice weeds without damaging the rice crop. Theprincipal weeds in rice crops, such as species of the genera Alisma,Ammania, Cyperus, Echinochloa, Eleocharis, Fimbristylis, Scirpus andMonochoria, are destroyed selectively both in the preemergence and thepostemergence method

There is therefore proposed according to the present invention a novelsynergistic composition for the selective control of weeds thatcontains, in admixture with one another, as active ingredient, on theone handN-[2-(2-methoxyethoxy)-phenylsulphonyl]-N'-(4,6-dimethoxy-1,3,5-triazin-2-yl)-ureaof the formula I ##STR17## and on the other hand an active ingredient ofthe formula II ##STR18## in which R¹ represents C₁ -C₄ -alkoxycarbonylor C₁ -C₄ -alkoxy, or an active ingredient of the formula III ##STR19##in which R² represents chlorine or methyl, or an active ingredient ofthe formula IV ##STR20## in which R³ represents ethyl or1,2-dimethylpropyl, or an active ingredient of the formula V ##STR21##in which R⁴ represents C₁ -C₄ -alkoxy or C₁ -C₄ -alkoxymethyl, or anactive ingredient of the formula VI ##STR22## in which R⁵ represents2-(2-chloroethoxy)-phenyl, 2-methoxycarbonylbenzyl or4-ethoxycarbonyl-1-methyl-5-pyrazolyl, R⁶ represents methoxy or methyland A represents nitrogen or the methine group, or an active ingredientof the formula VII ##STR23## in which R⁷ represents 1-piperidinyl,1-hexahydroazepinyl or diethylamino and R⁸ represents ethyl,4-chlorobenzyl or 1,1-dimethylbenzyl, or the compound of the formulaVIII ##STR24## or the compound of the formula IX ##STR25## or thecompound of the formula X ##STR26## or the compound of the formula XI##STR27## or the compound of the formula XII ##STR28## or the compoundof the formula XIII ##STR29## or the compound of the formula XIV##STR30## or the compound of the formula XV ##STR31##

It is extremely surprising that a combination of the active ingredientof the formula I and an active ingredient of the formula II, III, IV, V,VI, VII, VIII, IX, X, XI, XII, XIII, XIV or XV not only brings about anadditional broadening of the spectrum of action to cover weeds that arenormally associated with rice, which would be expected in principle, butalso achieves a synergistic effect that broadens the range of action ofboth preparations in two respects.

Firstly, the rates of application of the individual compounds I and II,III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV or XV are markedlyreduced while the high level of action is maintained unchanged and,secondly, the combined mixture still achieves a high degree of weedcontrol even where the two compounds individually are entirely withouteffect when the rates of application are too low. The result of this isa considerable broadening of the weed spectrum and an additionalincrease in the safety margin in rice, as is necessary and desirable incase of inadvertent overdosage of the active ingredient.

The composition according to the invention can be used both in ricecrops grown in water (paddy rice) and in rice crops grown on dry ground(upland rice).

The active ingredient combination according to the invention contains anactive ingredient of the formula I and an active ingredient of theformula II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV or XVin any mixture ratio, generally with an excess of the one component overthe other. The mixture ratio is of so little importance that bothexcesses of the component of the formula I and excesses of the componentof the formula II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIVor XV are tolerated. Preferred mixture ratios of active ingredient I tothe co-component of the formula II, III, IV, V, VI, VII, VIII, IX, X,XI, XII, XIII, XIV or XV are from 1:1 to 1:2000, especially from 1:5 to1:500. The active ingredient combinations according to the inventionexhibit outstanding action against weeds while having no appreciableeffect on the rice crops at the advantageously used rates of applicationof from 0.005 to 3 kg, preferably from 0.01 to 1 kg, per hectare.

Combinations of compound I with the following individual activeingredients have proved to be outstandingly effective synergistic activeingredient mixtures:

a) N-(butoxymethyl)-2-chloro-N-(2,6-diethylphenyl)acetamide [compoundVa];

b) N-(propoxyethyl)-2-chloro-N-(2,6-diethylphenyl)acetamide [compoundVb];

c) S-4-chlorobenzyl-N,N-diethylthiocarbamate [compound VIIc];

d) 3,7-dichloroquinoline-8-carboxylic acid [compound VIII];

e) 2-(2-benzothiazolyloxy)-N-methylacetanilide [compound XIII]; and

f) S-2-methylpiperidinocarbonylmethyl-O,O-dipropyldithiophosphoric acidester [compound XV].

Of the above, especially preferred synergistic combination partners ofthe compound of the formula I are the active ingredients Vb, VIIc, VIIIand XIII.

The formulations, i.e. the compositions or preparations containing theactive ingredient mixture according to the invention and, whereappropriate, a solid or liquid adjuvant, are manufactured in knownmanner, for example by intimately mixing and/or grinding the activeingredients with extenders, such as, for example, solvents, solidcarriers and, where appropriate, surface-active compounds (surfactants)

Suitable solvents are: aromatic hydrocarbons, preferably the fractionsC₈ to C₁₂, such as, for example, xylene mixtures or substitutednaphthalenes, phthalic acid esters, such as dibutyl or dioctylphthalate, aliphatic hydrocarbons, such as cyclohexane or paraffins,alcohols and glycols and their ethers and esters, such as ethanol,ethylene glycol, ethylene glycol monomethyl or monoethyl ether, ketones,such as cyclohexanone, strongly polar solvents, such asN-methyl-2-pyrrolidone, dimethyl sulphoxide or dimethylformamide, andalso optionally epoxidised vegetable oils, such as epoxidised coconutoil or soybean oil, or water.

The solid carriers used, for example for dusts and dispersible powders,are generally natural mineral fillers, such as calcite, talcum, kaolin,montmorillonite or attapulgite. In order to improve the physicalproperties it is also possible to add highly dispersed silicic acid orhighly dispersed absorbent polymers Suitable granulated adsorptivecarriers are porous types, such as, for example, pumice, broken brick,sepiolite or bentonite, and suitable nonsorbent carriers are, forexample, calcite or sand. In addition, it is possible to use a largenumber of pre-granulated materials of inorganic or organic nature, suchas, especially, dolomite or pulverised plant residues, such as, forexample, cork powder or sawdust.

Especially advantageous, application-facilitating adjuvants that canresult in a great reduction in the rates of application are also natural(animal or vegetable) or synthetic phospholipids from the series ofcephalins and lecithins, such as, for example, phosphatidylethanolamine,phosphatidylserine, phosphatidylcholine, sphingomyelin,phosphatidylinositol, phosphatidylglycerol, lysolecithin, plasmalogen orcardiolipin, which can be obtained, for example, from animal orvegetable cells, especially from the brain, heart, lung, liver, eggyolks or soybeans Commercial mixtures that can be used are, for example,phosphatidylcholine mixtures. Synthetic phospholipids are, for example,dioctanoylphosphatidylcholine and dipalmitoylphosphatidylcholine.

Suitable surface-active compounds are nonionic, cationic and/or anionicsurfactants having good emulsifying, dispersing and wetting properties.The term "surfactants" should also be understood as meaning mixtures ofsurfactants

Suitable anionic surfactants may be both so-called water-soluble soapsand water-soluble synthetic surface-active compounds.

There may be mentioned as soaps the alkali metal salts, alkaline earthmetal salts and unsubstituted or substituted ammonium salts of higherfatty acids (C₁₀ -C₂₂), such as, for example, the sodium or potassiumsalts of oleic or stearic acid, or of natural fatty acid mixtures, whichcan be obtained, for example, from coconut or tallow oil. Fatty acidmethyltaurine salts should also be mentioned.

So-called synthetic surfactants are, however, more often used,especially fatty sulphonates, fatty sulphates, sulphonated benzimidazolederivatives or alkylarylsulphonates.

The fatty sulphonates or fatty sulphates are generally in the form ofalkali metal salts, alkaline earth metal salts or unsubstituted orsubstituted ammonium salts and have an alkyl radical having from 8 to 22carbon atoms, alkyl also including the alkyl moiety of acyl radicals,for example the sodium or calcium salt of lignosulphonic acid, ofdodecylsulphuric acid ester or of a fatty alcohol sulphate mixtureproduced from natural fatty acids. These also include the salts ofsulphuric acid esters and sulphonic acids of fatty alcohol/ethyleneoxide adducts. The sulphonated benzimidazole derivatives containpreferably 2 sulphonic acid groups and one fatty acid radical havingfrom 8 to 22 carbon atoms Alkylarylsulphonates are, for example, thesodium, calcium or triethanolamine salts of dodecylbenzenesulphonicacid, of dibutylnaphthalenesulphonic acid or of a naphthalenesulphonicacid/formaldehyde condensation product.

Also suitable are corresponding phosphates, such as, for example, saltsof the phosphoric acid ester of an adduct of p-nonylphenol with from 4to 14 moles of ethylene oxide.

Suitable nonionic surfactants are especially polyglycol etherderivatives of aliphatic or cycloaliphatic alcohols, of saturated orunsaturated fatty acids and of alkylphenols, that may contain from 3 to30 glycol ether groups and from 8 to 20 carbon atoms in the (aliphatic)hydrocarbon radical and from 6 to 18 carbon atoms in the alkyl radicalof the alkylphenols.

Further suitable nonionic surfactants are the water-soluble adducts ofpolyethylene oxide with polypropylene glycol,ethylenediaminopolypropylene glycol and alkylpolypropylene glycolcontaining from 1 to 10 carbon atoms in the alkyl chain, which adductscontain from 20 to 250 ethylene glycol ether groups and from 10 to 100propylene glycol ether groups. The said compounds normally contain from1 to 5 ethylene glycol units per propylene glycol unit.

There may be mentioned as examples of nonionic surfactantsnonylphenolpolyethoxyethanols, castor oil polyglycol ethers,polypropylene/polyethylene oxide adducts,tributylphenoxypolyethoxyethanol, polyethylene glycol andoctylphenoxypolyethoxyethanol.

Also suitable are fatty acid esters of polyoxyethylenesorbitan, such aspolyoxyethylenesorbitan trioleate.

Cationic surfactants are especially quaternary ammonium salts thatcontain, as N-substituent, at least one alkyl radical having from 8 to22 carbon atoms and, as further substituents, lower unsubstituted orhalogenated alkyl, benzyl or lower hydroxyalkyl radicals. The salts arepreferably in the form of halides, methyl sulphates or ethyl sulphates,for example stearyltrimethylammonium chloride orbenzyldi(2-chloroethyl)-ethylammonium bromide.

The surfactants customarily employed in the art of formulation aredescribed, inter alia, in the following publications: "McCutcheon'sDetergents and Emulsifiers Annual" MC Publishing Corp., Ridgewood, N.J.,1981; H. Stache, "Tensid-Taschenbuch", 2nd Edition, C. Hanser Verlag,Munich, Vienna, 1981; M. and J. Ash "Encyclopedia of Surfactants", vols.I-III, Chemical Publishing Co., New York, 1980-1981.

The agrochemical preparations generally contain from 0.1 to 95%,especially from 0.1 to 80%, active ingredient mixture of the formulae Iand II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV or XV, from1 to 99.9% solid or liquid adjuvant and from 0 to 25%, especially from0.1 to 25%, surfactant.

Preferred formulations are composed especially of the followingconstituents (%=percentage by weight):

    ______________________________________                                        Emulsifiable concentrates                                                     active ingredient mixture                                                                     1-20%,    preferably 5-10%                                    surface-active agent                                                                          5-30%,    preferably 10-20%                                   liquid carrier  50-94%,   preferably 70-85%                                   Dusts                                                                         active ingredient mixture                                                                     0.1-10%,  preferably 0.1-1%                                   solid carrier   99.9-90%, preferably 99.9-99%                                 Suspension concentrates                                                       active ingredient mixture                                                                     5-75%,    preferably 10-50%                                   water           94-25%,   preferably 88-30%                                   surface-active agent                                                                          1-40%,    preferably 2-30%                                    Wettable powders                                                              active ingredient mixture                                                                     0.5-90%,  preferably 1-80%                                    surface-active agent                                                                          0.5-20%,  preferably 1-15%                                    solid carrier   5.0-95%,  preferably 15-90%                                   Granulates                                                                    active ingredient mixture                                                                     0.5-30%,  preferably 3-15%                                    solid carrier   99.5-70%, preferably 97-85%                                   ______________________________________                                    

Whereas commercial products will preferably be formulated asconcentrates, the end user will normally employ dilute formulations. Theforms of application can be diluted to concentrations as low as 0.001%active ingredient.

Other biocidal active ingredients or compositions can be mixed with thedescribed compositions according to the invention. For example, thenovel compositions may contain, in addition to the mentioned compoundsof the general formula I and of the formula II, III, IV, V, VI, VII,VIII, IX, X, XI, XII, XIII, XIV or XV, insecticides, fungicides,bactericides, fungistatics, bacteriostatics and nematocides in order tobroaden the spectrum of action. It is also possible to add antagonists(safeners) in order to protect the cultivated plants from inadvertentoverdoses of herbicides or herbicide mixtures.

The compositions according to the invention are generally formulated, indetail, in accordance with the following Examples

FORMULATION EXAMPLES EXAMPLE F1 Formulation Examples for SynergisticActive Ingredient Mixtures of the Formulae I and II, III, IV, V, VI,VII, VIII, IX, X, XI, XII, XIII, XIV or XV (%=percentage by weight)

    ______________________________________                                        a) Wettable powders                                                                           a)      b)      c)     d)                                     ______________________________________                                        active ingredient I                                                                           10%     20%     5%     30%                                    one of the active                                                                             10%     40%     15%    30%                                    ingredients II, III,                                                          IV, V, VI, VII, VIII,                                                         IX, X, XI, XII, XIII,                                                         XIV and XV                                                                    Na lignosulphonate                                                                             5%      5%     5%      5%                                    Na lauryl sulphate                                                                             3%     --      3%     --                                     Na diisobutylnaphthalene-                                                                     --       6%     --      6%                                    sulphonate                                                                    octylphenol polyethylene                                                                      --       2%     --      2%                                    glycol ether (7-8 mol EO)                                                     highly dispersed silicic                                                                       5%     27%     5%     27%                                    acid                                                                          kaolin          67%     --      67%    --                                     ______________________________________                                    

The active ingredient mixture is mixed well with the adjuvants andground well in a suitable mill. Wettable powders are obtained that canbe diluted with water to form suspensions of any desired concentration.

    ______________________________________                                        b) Emulsion concentrate                                                                         a)        b)      c)                                        ______________________________________                                        active ingredient I                                                                             5%        5%      12%                                       one of the active ingredients                                                                   5%        20%     13%                                       II, III, IV, V, VI, VII,                                                      VIII, IX, X, XI, XII, XIII,                                                   XIV and XV                                                                    octylphenol polyethylene                                                                        3%        3%       3%                                       glycol ether (4-5 mol EO)                                                     Ca dodecylbenzenesul-                                                                           3%        3%       2%                                       phonate castor oil polyglycol                                                 ether (36 mol EO) 4%        4%       4%                                       cyclohexanone     30%       30%     31%                                       xylene mixture    50%       35%     35%                                       ______________________________________                                    

Emulsions of any desired concentration can be produced from theseconcentrates by dilution with water.

    ______________________________________                                        c) Dusts        a)      b)       c)    d)                                     ______________________________________                                        active ingredient I                                                                           2%      4%       2%    4%                                     one of the active                                                                             3%      4%       4%    8%                                     ingredients II, III, IV,                                                      V, VI, VII, VIII, IX, X,                                                      XI, XII, XIII, XIV and XV                                                     talcum          95%     --       94%   --                                     kaolin          --      92%      --    88%                                    ______________________________________                                    

Ready-for-use dusts are obtained by mixing the active ingredient mixturewith the carrier and grinding the mixture in a suitable mill.

    ______________________________________                                        d) Extruder granulate                                                                           a)       b)       c)                                        ______________________________________                                        active ingredient I                                                                             5%       3%       5%                                        one of the active ingredients II,                                                               5%       7%       15%                                       III, IV, V, VI, VII, VIII, IX, X,                                             XI, XII, XIII, XIV and XV                                                     Na lignosulphonate                                                                              2%       2%       2%                                        carboxymethylcellulose                                                                          1%       1%       1%                                        kaolin            87%      87%      77%                                       ______________________________________                                    

The active ingredient mixture is mixed and ground with the adjuvants,and moistened with water. The mixture is extruded and then dried in astream of air.

    ______________________________________                                        e) Coated granulate    a)     b)                                              ______________________________________                                        active ingredient I    1.5%   3%                                              one of the active ingredients II,                                                                    1.5%   5%                                              III, IV, V, VI, VII, VIII, IX, X, XI,                                         XII, XIII, XIV and XV                                                         polyethylene glycol (MW 200)                                                                           3%   3%                                              kaolin                  94%   89%                                             ______________________________________                                    

The finely ground active ingredient mixture is applied uniformly, in amixer, to the kaolin, which has been moistened with polyethylene glycol.Dust-free coated granulates are thus obtained.

    ______________________________________                                        f) Suspension concentrate                                                                            a)       b)                                            ______________________________________                                        active ingredient I    20%      20%                                           one of the active ingredients II,                                                                    20%      40%                                           III, IV, V, VI, VII, VIII, IX, X, XI,                                         XII, XIII, XIV and XV                                                         ethylene glycol        10%      10%                                           nonylphenol polyethylene glycol ether                                                                 6%       6%                                           (15 mol EO)                                                                   Na lignosulphonate     10%      10%                                           carboxymethylcellulose  1%       1%                                           37% aqueous formaldehyde solution                                                                     0.2%     0.2%                                         silicone oil in the form of a 75%                                                                     0.8%     0.8%                                         aqueous emulsion                                                              water                  32%      12%                                           ______________________________________                                    

The finely ground active ingredient mixture is intimately mixed with theadjuvants. A suspension concentrate is thus obtained from whichsuspensions of any desired concentration can be produced by dilutionwith water.

A synergistic effect is always present in the case of herbicides whenthe herbicidal action of the active ingredient combination of I and II,III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV or XV is greaterthan the total action of the active ingredients applied individually.

The expected herbicidal action E for a given combination of twoherbicides can be calculated as follows (cf. COLBY, S. R., "Calculatingsynergistic and antagonistic response of herbicide combinations", Weeds15, pages 20-22, 1967): ##EQU1## in which: X=percentage inhibition ofgrowth in the case of treatment with a herbicide I at a rate ofapplication of p kg per hectare in comparison with the untreated control(=0%)

Y=percentage inhibition of growth in the case of treatment with aherbicide II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV or XVat a rate of application of g kg per hectare in comparison with theuntreated control

E=expected herbicidal action (percentage inhibition of growth incomparison with the untreated control) after treatment with herbicidemixture I and II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIVor XV at a rate of application of p+q kg active ingredient per hectare

If the action actually observed is greater than the expected value E,then synergism has been achieved

The synergistic effect ascertained in the case of the above componentsaccording to the invention in mixtures of two active ingredients is alsoobserved in mixtures of three active ingredient components. Suchthree-component mixtures form a further aspect of the present invention.

The synergistic three-component compositions according to the inventionfor selective weed control are characterised in that they contain, inadmixture with one another, as active ingredient, on the one handN-[2-(2-methoxyethoxy)-phenylsulphonyl]-N'-(4,6-dimethoxy-1,3,5-triazin-2-yl)-ureaof the formula I ##STR32## and on the other hand two active ingredientsselected from the series consisting of the compounds of the formula II##STR33## in which R¹ represents C₁ -C₄ -alkoxycarbonyl or C₁ -C₄-alkoxy, the compounds of the formula III ##STR34## in which R²represents chlorine or methyl, the compounds of the formula IV ##STR35##in which R³ represents ethyl or 1,2-dimethylpropyl, the compounds of theformula V ##STR36## in which R⁴ represents C₁ -C₄ -alkoxy or C₁ -C₄-alkoxymethyl, the compounds of the formula VI ##STR37## in which R⁵represents 2-(2-chloroethoxy)-phenyl, 2-methoxycarbonylbenzyl or4-ethoxycarbonyl-1-methyl-5-pyrazolyl, R⁶ represents methoxy or methyland A represents nitrogen or the methine group, the compounds of theformula VII ##STR38## in which R⁷ represents 1-piperidinyl,1-hexahydroazepinyl or diethylamino and R⁸ represents ethyl,4-chlorobenzyl or 1,1-dimethylbenzyl, the compound of the formula VIII##STR39## the compound of the formula IX ##STR40## the compound of theformula X ##STR41## the compound of the formula XI ##STR42## thecompound of the formula XII ##STR43## the compound of the formula XIII##STR44## the compound of the formula XIV ##STR45## the compound of theformula XV ##STR46##

It is extremely surprising that a combination of the active ingredientof the formula I and two active ingredients of the formulae II, III, IV,V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, and XV not only bringsabout an additional broadening of the spectrum of action to cover weedsthat are normally associated with rice, which would be expected inprinciple, but also achieves a synergistic effect.

The expected herbicidal action of a three-component mixture can becalculated according to DE-OS 34 19 050 by means of the followingformula ##EQU2## In that formula the symbols E, X and Y have themeanings given above while Z has the same meaning as Y with the provisothat a different herbicide is selected from the series II, III, IV, V,VI, VII, VIII, IX, X, XI, XII, XIII, XIV and XV from that chosen in thecase of Y.

If the action actually observed is greater than the expected value E,then synergism has also been achieved in the case of a three-componentmixture

The three-component active ingredient mixtures according to theinvention can be formulated in accordance with the same principles ascan the two-component mixtures.

The mixture ratios of the three-component mixtures are to a great extentunimportant. As a rule, the amount of component I is less than theamount of the other two components of the mixture. For example, thecomponents of the mixture are generally in ratios of from 1:1:1 to1:100:100. The first figure represents the compound of the formula I andthe other two figures represent the two co-components from the seriesconsisting of the compounds of the formulae II, III, IV, V, VI, VII,VIII, IX, X, XI, XII, XIII, XIV and XV. The mixture ratios arepreferably from 1:5:5 to 1:20:20.

The preferred co-components for the compounds of the formula I are inthe group

2,4-dichlorophenoxyacetic acid (compound IIIa)

N-(propoxyethyl)-2-chloro-N-(2,6-diethylphenyl)-acetamide (compound Vb),

S-ethyl-N,N-hexamethylene thiocarbamate (compound VIIa),

3,7-dichloroquinoline-8-carboxylic acid (compound VIII),

3,4-dichloropropionanilide (compound XIV), and

S-2-methylpiperidinocarbonylmethyl-O,O-dipropyldithiophosphoric acidester (compound XV).

Preferred mixtures having three active ingredient components are

compound I with compounds Vb and XV,

compound I with compounds VIII and XV,

compound I with compounds Vb and VIII,

compound I with compounds XIV and XV, and

compound I with compounds IIIa and XV.

The mixture that is especially preferred contains, together with activeingredient I, compounds Vb and VIII.

The rates of application of the three-component mixtures according tothe invention are from 0.005 to 3 kg, preferably from 0.01 to 1 kg, perhectare.

The synergistic effect of the combinations of the active ingredients Iand II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV or XV isdemonstrated in the following Examples.

In order to simplify the structure of the tests and to obtain a betterbasis for comparison, in addition to the cultivated plant, rice, eitherMonochoria vaginalis or Scirpus juncoides was selected as arepresentative example of the weeds.

BIOLOGICAL EXAMPLES EXAMPLE B1: Greenhouse Test

25-day-old rice plants of the type "Yamabiko" were planted in largecontainers in a greenhouse Seeds of the rice weed Monochoria were sownbetween the rice plants. The containers were then watered and coveredwith a layer of water 2.5 cm deep Three days after planting the rice andsowing the seeds a diluted concentrate of the active ingredients wasadded to the covering layer of water in amounts given in rate ofapplication per hectare The containers were kept covered with water at atemperature of 25° C. and at high air humidity until an evaluation wascarried out 11 days later. The percentage inhibition of growth wasrecorded in comparison with the untreated control. The following linearscale was used as a standard:

    ______________________________________                                                100% = plants killed                                                           50% = mean effect                                                             0% = as untreated control                                            ______________________________________                                    

The results of the test are shown together with the expected values,calculated in accordance with the above-mentioned Colby formula, in theTables in sections a, b, c, d and e The Tables indicate the amounts ofactive ingredient applied in each case and the plants tested. Each ofsections a, b, c, d and e contains three Tables The first two Tablesshow the results obtained with the individual active ingredients and thethird Table gives the expected values calculated according to Colby inaccordance with the values ascertained experimentally.

a) Activity of mixtures I with Va Evaluation: 11 days after applicationin percentage inhibition of growth in comparison with the untreatedcontrol

    ______________________________________                                        Compound I                                                                    g a.i./ha    16       8     4      2   1                                      ______________________________________                                        "Yamabiko" rice                                                                             0        0     0     0   0                                      Monochoria   50       30    30     0   0                                      ______________________________________                                        Compound Va                                                                   g a.i./ha    60       30    15     8   4                                      ______________________________________                                        "Yamabiko" rice                                                                             0        0     0     0   0                                      Monochoria   40       20     0     0   0                                      ______________________________________                                        rates of application                                                          in g a.i./ha "Yamabiko" rice                                                                             Monochoria                                         comp.  comp.     effect  expected                                                                              effect                                                                              expected                               I      Va        found   value   found value                                  ______________________________________                                        16     60        0       0       80    70                                     8      60        0       0       75    58                                     4      60        0       0       75    58                                     2      60        0       0       50    40                                     1      60        0       0       40    40                                     16     30        0       0       85    60                                     8      30        0       0       75    44                                     4      30        0       0       55    44                                     2      30        0       0       40    20                                     1      30        0       0       20    20                                     16     15        0       0       90    50                                     8      15        0       0       80    30                                     4      15        0       0       80    30                                     2      15        0       0       60     0                                     1      15        0       0       40     0                                     16      8        0       0       80    50                                     8       8        0       0       75    30                                     4       8        0       0       50    30                                     2       8        0       0       30     0                                     1       8        0       0        0     0                                     16      4        0       0       90    50                                     8       4        0       0       85    30                                     4       4        0       0       60    30                                     2       4        0       0       30     0                                     1       4        0       0        0     0                                     ______________________________________                                    

b) Activity of mixtures I with Vb Evaluation: 11 days after applicationin percentage inhibition of growth in comparison with the untreatedcontrol

    ______________________________________                                        Compound I                                                                    g a.i./ha    16       8     4      2   1                                      ______________________________________                                        "Yamabiko" rice                                                                             0        0     0     0   0                                      Monochoria   50       30    30     0   0                                      ______________________________________                                        Compound Vb                                                                   g a.i./ha    16          8     4                                              ______________________________________                                        "Yamabiko" rice                                                                             0           0    0                                              Monochoria   30          20    0                                              ______________________________________                                        rates of application                                                          in g a.i./ha "Yamabiko" rice                                                                             Monochoria                                         comp.  comp.     effect  expected                                                                              effect                                                                              expected                               I      Vb        found   value   found value                                  ______________________________________                                        16     16        0       0       90    65                                     8      16        0       0       80    51                                     4      16        0       0       90    51                                     2      16        0       0       80    30                                     1      16        0       0       20    30                                     16      8        0       0       80    60                                     8       8        0       0       70    44                                     4       8        0       0       70    40                                     2       8        0       0       50    20                                     1       8        0       0       20    20                                     16      4        0       0       70    30                                     8       4        0       0       60    30                                     4       4        0       0       60    30                                     2        4       0       0       30     0                                     1       4        0       0       10     0                                     ______________________________________                                    

c) Activity of mixtures I with VIIc Evaluation: 11 days afterapplication in percentage inhibition of growth in comparison with theuntreated control

    ______________________________________                                        Compound I                                                                    g a.i./ha    16        8      4      2   1                                    ______________________________________                                        "Yamabiko" rice                                                                             0         0      0     0   0                                    Monochoria   50        30     30     0   0                                    ______________________________________                                        Compound VIIc                                                                 g a.i./ha    250       125    60     30  15                                   ______________________________________                                        "Yamabiko" rice                                                                             0         0      0     0   0                                    Monochoria    0         0      0     0   0                                    ______________________________________                                        rates of application                                                          in g a.i./ha "Yamabiko" rice                                                                             Monochoria                                         comp.  comp.     effect  expected                                                                              effect                                                                              expected                               I      VIIc      found   value   found value                                  ______________________________________                                        16     250       0       0       100   50                                     8      250       0       0       95    30                                     4      250       0       0       95    30                                     2      250       0       0       85     0                                     1      250       0       0       50     0                                     16     125       0       0       95    50                                     8      125       0       0       90    30                                     4      125       0       0       90    30                                     2      125       0       0       85     0                                     1      125       0       0        0     0                                     16      60       0       0       90    50                                     8       60       0       0       90    30                                     4       60       0       0       90    30                                     2       60       0       0       80     0                                     1       60       0       0       40     0                                     16      30       0       0       85    50                                     8       30       0       0       80    30                                     4       30       0       0       80    30                                     2       30       0       0       60     0                                     1       30       0       0       40     0                                     16      15       0       0       80    50                                     8       15       0       0       80    30                                     4       15       0       0       80    30                                     2       15       0       0       50     0                                     1       15       0       0       20     0                                     ______________________________________                                    

d) Activity of mixtures I with XIII Evaluation: 11 days afterapplication in percentage inhibition of growth in comparison with theuntreated control

    ______________________________________                                        Compound I                                                                    g a.i./ha    16       8     4      2   1                                      ______________________________________                                        "Yamabiko" rice                                                                             0        0     0     0   0                                      Monochoria   50       30    30     0   0                                      ______________________________________                                        Compound XIII                                                                 g a.i./ha    60       30    15     8   4                                      ______________________________________                                        "Yamabiko" rice                                                                             0        0     0     0   0                                      Monochoria   10        0     0     0   0                                      ______________________________________                                        rates of application                                                          in g a.i./ha "Yamabiko" rice                                                                             Monochoria                                         comp.  comp.     effect  expected                                                                              effect                                                                              expected                               I      XIII      found   value   found value                                  ______________________________________                                        16     60        0       0       100   55                                     8      60        0       0       98    37                                     4      60        0       0       95    37                                     2      60        0       0       80    10                                     1      60        0       0       30    10                                     16     30        0       0       95    50                                     8      30        0       0       95    30                                     4      30        0       0       90    30                                     2      30        0       0       75     0                                     1      30        0       0       20     0                                     16     15        0       0       100   50                                     8      15        0       0       95    30                                     4      15        0       0       90    30                                     2      15        0       0       70     0                                     1      15        0       0       20     0                                     16      8        0       0       95    50                                     8       8        0       0       85    30                                     4       8        0       0       70    30                                     2       8        0       0       50     0                                     1       8        0       0        0     0                                     16      4        0       0       90    50                                     8       4        0       0       80    30                                     4       4        0       0       70    30                                     2       4        0       0       40     0                                     1       4        0       0        0     0                                     ______________________________________                                    

e) Activity of mixtures I with XV Evaluation: 11 days after applicationin percentage inhibition of growth in comparison with the untreatedcontrol

    ______________________________________                                        Compound I                                                                    g a.i./ha    16        8      4      2   1                                    ______________________________________                                        "Yamabiko" rice                                                                             0         0      0     0   0                                    Monochoria   50        30     30     0   0                                    ______________________________________                                        Compound XV                                                                   g a.i./ha    250       125    60     30  15                                   ______________________________________                                        "Yamabiko" rice                                                                             0         0      0     0   0                                    Monochoria   10         0      0     0   0                                    ______________________________________                                        rates of application                                                          in g a.i./ha "Yamabiko" rice                                                                             Monochoria                                         comp.  comp.     effect  expected                                                                              effect                                                                              expected                               I      XV        found   value   found value                                  ______________________________________                                        16     250       0       0       95    55                                     8      250       0       0       90    37                                     4      250       0       0       90    37                                     2      250       0       0       85    10                                     1      250       0       0       70    10                                     16     125       0       0       95    50                                     8      125       0       0       95    30                                     4      125       0       0       90    30                                     2      125       0       0       85     0                                     1      125       0       0       60     0                                     16      60       0       0       95    50                                     8       60       0       0       90    30                                     4       60       0       0       90    30                                     2       60       0       0       85     0                                     1       60       0       0       60     0                                     16      30       0       0       90    50                                     8       30       0       0       90    30                                     4       30       0       0       85    30                                     2       30       0       0       80     0                                     1       30       0       0       30     0                                     16      15       0       0       90    50                                     8       15       0       0       80    30                                     4       15       0       0       75    30                                     2       15       0       0       70     0                                     1       15       0       0       40     0                                     ______________________________________                                    

EXAMPLE B2 Field Test in Paddy Rice

Test plots each having a surface area of 10 m² were ploughed, floodedwith water and prepared for planting with rice by puddling the surfaceof the soil. The plots were planted with 21-day-old rice plants of thetype "Nihonbare" that were at the 2-3 leaf stage. 12 days afterplanting, the tests plots were sprayed with a dilute aqueous dispersionof the active ingredient mixture. The plots were maintained in theflooded state. 33 days after the treatment, an evaluation was carriedout in accordance with the standard given in the greenhouse test incomparison with the untreated control plot which had natural weedgrowth. The principal weed was Scirpus juncoides.

    ______________________________________                                        Results:                                                                      test site:     Ono, central Japan                                             type of rice:  Nihonbare                                                      planting date: 25th April 1986                                                application:   7th May 1986                                                   evaluation:    9th June 1986                                                  rate of application in the form of spray liquor mixture                       (tank mix):                                                                   compound I:     30 g active ingredient/hectare                                compound Vb:   300 g active ingredient/hectare                                compound VIII: 250 g active ingredient/hectare                                                   effect on                                                  active             "Nihonbare"                                                                              effect on                                       ingredient                                                                            g a.i./ha  rice       Scirpus juncoides                               ______________________________________                                        comp. I  30        0          90                                              comp. Vb                                                                              300        0          20                                              comp. VIII                                                                            250        0           0                                              ______________________________________                                                    effect of the mixture                                                         30 g comp. I + 300 g comp.                                                    Vb + 250 g comp. VIII                                                           effect found                                                                            expected value                                        ______________________________________                                        "Nihonbare" rice                                                                             0         0                                                    Scirpus juncoides                                                                           100       92                                                    ______________________________________                                    

We claim:
 1. A synergistic composition for selective weed control inrice, which comprises, in addition to a carrier or other adjuvants, inadmixture with one another, as active component, on the one handN-[2-(2-methoxyethoxy)-phenylsulphonyl]-N'-(4,6-dimethoxy-1,3,5-triazin-2-yl)-ureaof the formula I ##STR47## and on the other hand an active ingredient ofthe formula VII ##STR48## in which R⁷ represents diethylamino and R⁸represents, 4-chlorobenzyl said active component being present in atleast a herbicidally effective amount.
 2. A composition according toclaim 1, wherein component I is present in said composition in a ratioby weight of from 1:1 to 1:250 with respect to the second component ofthe formula VII.
 3. A method for selective weed control in rice, whereinthe rice crop area is treated before the plants emerge with aherbicidally effective amount of a synergistic composition according toclaim
 1. 4. A method according to claim 3, wherein the rice crop area istreated with the said composition at rates of application correspondingto from 0.01 to 0.3 kg total amount of active ingredient per hectare.